1. Field of the Invention
The present invention relates to a composition for a light-scattering film used for forming a light-scattering film included in a reflection type liquid crystal display device and to a light-scattering film.
2. Description of the Related Art
In recent years, liquid crystal display devices have been widely propagated, large-scaled and come to be used outdoors. Thus, improvements have been required for the liquid crystal display devices in respect of, for example, weatherability, visibility, resistance to stains and resistance to heat under the conditions under which the liquid crystal display devices are used. Particularly, an improvement in the visibility is important, because the visibility is related to the main function of the liquid crystal display devices. Accordingly, extensive studies are being made in an attempt to improve the visibility of liquid crystal display devices.
For example, in a reflection type liquid crystal display device, e.g., an anti-reflection film, a light diffusion film and a light-scattering film, in which fine particles having a refractive index different from that of the base resin are dispersed in a base resin, are provided to control the reflection, diffusion and scattering of light, in order to improve the visibility.
More specifically, the reflection type liquid crystal display device requires a light reflector for reflecting, e.g., indoor light and external light, which are incident on the device. Two functions, i.e., light reflecting function and light scattering function, are required for the reflector. A light-scattering film is used as a member performing the light scattering function. This film comprises a transparent resin in which fine particles different from the transparent resin in refractive index are dispersed. For example, Japanese Patent Disclosure (Kokai) No. 2001-194514, Japanese Patent Disclosure No. 2002-258014 and Japanese Patent Disclosure No. 2002-258274 disclose a light-scattering film in which transparent particles (for example, inorganic particles such as silica particles or alumina particles or resin particles such as silicone resin particles, melamine resin particles or fluororesin particles) are dispersed in a transparent resin such as an acrylic resin, a fluoroacrylic resin, or an epoxy acrylic resin.
Excellent light scattering properties and excellent light transmitting properties are required for the light-scattering film. The light scattering film exhibits better light scattering properties when difference in the refractive index between the base resin and the fine particles are larger. The light scattering properties are greatly influenced by the particle diameter and the particle size distribution of the fine particles.
However, the conventional light-scattering film was not sufficiently satisfactory in respect of the light scattering properties and the surface smoothness.